/*
 * synergy -- mouse and keyboard sharing utility
 * Copyright (C) 2016 Symless Ltd.
 * 
 * This package is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * found in the file LICENSE that should have accompanied this file.
 * 
 * This package is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "platform/OSXUchrKeyResource.h"

#include <Carbon/Carbon.h>

//
// OSXUchrKeyResource
//

OSXUchrKeyResource::OSXUchrKeyResource(const void* resource,
				UInt32 keyboardType) :
	m_m(NULL),
	m_cti(NULL),
	m_sdi(NULL),
	m_sri(NULL),
	m_st(NULL)
{
	m_resource = static_cast<const UCKeyboardLayout*>(resource);
	if (m_resource == NULL) {
		return;
	}

	// find the keyboard info for the current keyboard type
	const UCKeyboardTypeHeader* th = NULL;
	const UCKeyboardLayout* r = m_resource;
	for (ItemCount i = 0; i < r->keyboardTypeCount; ++i) {
		if (keyboardType >= r->keyboardTypeList[i].keyboardTypeFirst &&
			keyboardType <= r->keyboardTypeList[i].keyboardTypeLast) {
			th = r->keyboardTypeList + i;
			break;
		}
		if (r->keyboardTypeList[i].keyboardTypeFirst == 0) {
			// found the default.  use it unless we find a match.
			th = r->keyboardTypeList + i;
		}
	}
	if (th == NULL) {
		// cannot find a suitable keyboard type
		return;
	}

	// get tables for keyboard type
	const UInt8* const base = reinterpret_cast<const UInt8*>(m_resource);
	m_m   = reinterpret_cast<const UCKeyModifiersToTableNum*>(base +
								th->keyModifiersToTableNumOffset);
	m_cti = reinterpret_cast<const UCKeyToCharTableIndex*>(base +
								th->keyToCharTableIndexOffset);
	m_sdi = reinterpret_cast<const UCKeySequenceDataIndex*>(base +
								th->keySequenceDataIndexOffset);
	if (th->keyStateRecordsIndexOffset != 0) {
		m_sri = reinterpret_cast<const UCKeyStateRecordsIndex*>(base +
								th->keyStateRecordsIndexOffset);
	}
	if (th->keyStateTerminatorsOffset != 0) {
		m_st = reinterpret_cast<const UCKeyStateTerminators*>(base +
								th->keyStateTerminatorsOffset);
	}

	// find the space key, but only if it can combine with dead keys.
	// a dead key followed by a space yields the non-dead version of
	// the dead key.
	m_spaceOutput = 0xffffu;
	UInt32 table  = getTableForModifier(0);
	for (UInt32 button = 0, n = getNumButtons(); button < n; ++button) {
		KeyID id = getKey(table, button);
		if (id == 0x20) {
			UCKeyOutput c =
				reinterpret_cast<const UCKeyOutput*>(base +
								m_cti->keyToCharTableOffsets[table])[button];
			if ((c & kUCKeyOutputTestForIndexMask) ==
								kUCKeyOutputStateIndexMask) {
				m_spaceOutput = (c & kUCKeyOutputGetIndexMask);
				break;
			}
		}
	}
}

bool
OSXUchrKeyResource::isValid() const
{
	return (m_m != NULL);
}

UInt32
OSXUchrKeyResource::getNumModifierCombinations() const
{
	// only 32 (not 256) because the righthanded modifier bits are ignored
	return 32;
}

UInt32
OSXUchrKeyResource::getNumTables() const
{
	return m_cti->keyToCharTableCount;
}

UInt32
OSXUchrKeyResource::getNumButtons() const
{
	return m_cti->keyToCharTableSize;
}

UInt32
OSXUchrKeyResource::getTableForModifier(UInt32 mask) const
{
	if (mask >= m_m->modifiersCount) {
		return m_m->defaultTableNum;
	}
	else {
		return m_m->tableNum[mask];
	}
}

KeyID
OSXUchrKeyResource::getKey(UInt32 table, UInt32 button) const
{
	assert(table < getNumTables());
	assert(button < getNumButtons());

	const UInt8* const base   = reinterpret_cast<const UInt8*>(m_resource);
	const UCKeyOutput* cPtr = reinterpret_cast<const UCKeyOutput*>(base +
								m_cti->keyToCharTableOffsets[table]);

  const UCKeyOutput c = cPtr[button];

	KeySequence keys;
	switch (c & kUCKeyOutputTestForIndexMask) {
	case kUCKeyOutputStateIndexMask:
		if (!getDeadKey(keys, c & kUCKeyOutputGetIndexMask)) {
			return kKeyNone;
		}
		break;

	case kUCKeyOutputSequenceIndexMask:
	default:
		if (!addSequence(keys, c)) {
			return kKeyNone;
		}
		break;
	}

	// XXX -- no support for multiple characters
	if (keys.size() != 1) {
		return kKeyNone;
	}

	return keys.front();
}

bool
OSXUchrKeyResource::getDeadKey(
	KeySequence& keys, UInt16 index) const
{
	if (m_sri == NULL || index >= m_sri->keyStateRecordCount) {
		// XXX -- should we be using some other fallback?
		return false;
	}

	UInt16 state = 0;
	if (!getKeyRecord(keys, index, state)) {
		return false;
	}
	if (state == 0) {
		// not a dead key
		return true;
	}

	// no dead keys if we couldn't find the space key
	if (m_spaceOutput == 0xffffu) {
		return false;
	}

	// the dead key should not have put anything in the key list
	if (!keys.empty()) {
		return false;
	}

	// get the character generated by pressing the space key after the
	// dead key.  if we're still in a compose state afterwards then we're
	// confused so we bail.
	if (!getKeyRecord(keys, m_spaceOutput, state) || state != 0) {
		return false;
	}

	// convert keys to their dead counterparts
	for (KeySequence::iterator i = keys.begin(); i != keys.end(); ++i) {
		*i = synergy::KeyMap::getDeadKey(*i);
	}

	return true;
}

bool
OSXUchrKeyResource::getKeyRecord(
	KeySequence& keys, UInt16 index, UInt16& state) const
{
	const UInt8* const base = reinterpret_cast<const UInt8*>(m_resource);
	const UCKeyStateRecord* sr =
		reinterpret_cast<const UCKeyStateRecord*>(base +
								m_sri->keyStateRecordOffsets[index]);
	const UCKeyStateEntryTerminal* kset =
		reinterpret_cast<const UCKeyStateEntryTerminal*>(sr->stateEntryData);

	UInt16 nextState = 0;
	bool found       = false;
	if (state == 0) {
		found     = true;
		nextState = sr->stateZeroNextState;
		if (!addSequence(keys, sr->stateZeroCharData)) {
			return false;
		}
	}
	else {
		// we have a next entry
		switch (sr->stateEntryFormat) {
		case kUCKeyStateEntryTerminalFormat:
			for (UInt16 j = 0; j < sr->stateEntryCount; ++j) {
				if (kset[j].curState == state) {
					if (!addSequence(keys, kset[j].charData)) {
						return false;
					}
					nextState = 0;
					found     = true;
					break;
				}
			}
			break;

		case kUCKeyStateEntryRangeFormat:
			// XXX -- not supported yet
			break;

		default:
			// XXX -- unknown format
			return false;
		}
	}
	if (!found) {
		// use a terminator
		if (m_st != NULL && state < m_st->keyStateTerminatorCount) {
			if (!addSequence(keys, m_st->keyStateTerminators[state - 1])) {
				return false;
			}
		}
		nextState = sr->stateZeroNextState;
		if (!addSequence(keys, sr->stateZeroCharData)) {
			return false;
		}
	}

	// next
	state = nextState;

	return true;
}

bool
OSXUchrKeyResource::addSequence(
	KeySequence& keys, UCKeyCharSeq c) const
{
	if ((c & kUCKeyOutputTestForIndexMask) == kUCKeyOutputSequenceIndexMask) {
		UInt16 index = (c & kUCKeyOutputGetIndexMask);
		if (index < m_sdi->charSequenceCount &&
			m_sdi->charSequenceOffsets[index] !=
				m_sdi->charSequenceOffsets[index + 1]) {
			// XXX -- sequences not supported yet
			return false;
		}
	}

	if (c != 0xfffe && c != 0xffff) {
		KeyID id = unicharToKeyID(c);
		if (id != kKeyNone) {
			keys.push_back(id);
		}
	}

	return true;
}
